1. Field of the Invention
The present invention relates to a guide apparatus for use in a folder equipped with a cutting cylinder, a collect cylinder, a jaw cylinder, and a paper guide in a rotary press.
2. Description of the Related Art
A conventional folder of a rotary press, particularly a folder equipped with a cutting cylinder, a collect cylinder, a jaw cylinder, and a paper guide, is disclosed in, for example, Japanese Utility Model Application Laid-Open (kokai) No. 2-119463.
In the folder disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 2-119463, a web which is fed to a gap between the collect cylinder and the cutting cylinder is cut by the cutting cylinder into sheets. A lead portion of each sheet is held on the collect cylinder by a pin which is provided on the collect cylinder and is stuck into the lead portion. After the lead portion of the sheet passes the position of the minimum gap between the neighboring collect cylinder and jaw cylinder as a result of rotation of the collect cylinder, a central portion of the sheet is pressed by a tucking blade provided on the collect cylinder toward a jaw mechanism composed of a movable jaw and a stationary jaw and provided on the jaw cylinder. As a result, the central portion of the sheet is held by the jaw mechanism. After the pin which has been holding the lead portion of the sheet is withdrawn from the lead portion, the lead portion is separated from the outer circumferential surface of the collect cylinder and begins to move toward the jaw cylinder.
A paper guide formed of a brush is disposed above the collect cylinder and the jaw cylinder in such a manner that the paper guide extends continuously from the vicinity of the outer circumferential surface of the collect cylinder to the vicinity of the outer circumferential surface of the jaw cylinder. The lead portion of the sheet which has left the collect cylinder moves toward the jaw cylinder while being guided along the side of the paper guide which faces the outer circumferential surfaces of the folding and jaw cylinders.
However, the guide apparatus for use in a folder disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 2-119463 involves the following problems.
In the guide apparatus, when the pin which has been holding the lead portion of a sheet is withdrawn from the lead portion, the lead portion of the sheet becomes free. Therefore, when the printing speed of the rotary press is very low, as shown in FIGS. 7 and 8, slack 30 or a curl 31 arises at a lead portion Q1xe2x80x2 of the sheet. When the lead portion Q1xe2x80x2 of the sheet moves toward a jaw cylinder G while having the slack 30 or the curl 31, the sheet is folded in a defective manner to thereby become a defectively folded sheet Rxe2x80x2 as shown in FIG. 9.
Particularly, when the rotary press is halted, the slack 30 or the curl 31, which arises at the lead portion Q1xe2x80x2 of the sheet at low printing speed as shown in FIGS. 7, 8, and 9, occurs more significantly. Subsequently, when the jaw cylinder G and the collect cylinder F resume rotating upon restart of the rotary press, the lead portion Q1xe2x80x2 of the sheet having the slack 30 or the curl 31 moves toward the jaw cylinder G. The slack 30 or the curl 31 is caught in the gap between a paper guide 10 and the outer circumferential surface of the jaw cylinder G, resulting in formation of the defectively folded sheet Rxe2x80x2. The defectively folded sheet Rxe2x80x2 is jammed in the gap, causing mechanical breakage.
Thus, in printing preparation work (such as paper-threading work or printing adjustment work), which involves frequent start and stop of low-printing-speed operation, a worker must always observe the folder in preparation in order to remove defectively folded sheets discharged to the outside of the machine and to deal with jamming of defectively folded sheets. As a result, the burden imposed on the worker increases, and work efficiency is impaired.
In view of the foregoing, an object of the present invention is to provide a guide apparatus for use in a folder for preventing occurrence of a defectively folded sheet to thereby prevent occurrence of paper jam on a jay cylinder.
Another object of the present invention is to provide a guide apparatus for use in a folder which does not require a worker to observe a folder during printing preparation work, to thereby achieve laborsaving and enhancement of work efficiency.
To achieve the above objects, the present invention provides a guide apparatus for use in a folder in which a cutting cylinder and a jaw cylinder are disposed around a collect cylinder such that a gap is formed between the cutting cylinder and the collect cylinder and between the jaw cylinder face and the collect cylinder; pairs each consisting of a cutting bar extending axially and a pin are circumferentially arranged on an outer circumferential surface of the collect cylinder at circumferential intervals each corresponding to a length of a sheet such that the pins are projectable from an outer circumferential surface of the collect cylinder at locations adjacent to and behind the corresponding cutting bars in the rotational direction of the collect cylinder; tucking blades extending axially are each disposed at a substantially circumferentially central position between adjacent two of the cutting bars to be projectable from the outer circumferential surface of the collect cylinder; a knife extending axially projects from the outer circumferential surface of the cutting cylinder; jaw mechanisms are circumferentially arranged on the outer circumferential surface of the jaw cylinder at circumferential intervals each corresponding to the length of a sheet; a paper guide is disposed over an appropriate range covering a portion of the outer circumferential surface of the collect cylinder and a portion of the outer circumferential surface of the jaw cylinder, which portions are located downstream of a narrowest gap between the collect cylinder and the jaw cylinder with respect to rotational directions of the collect cylinder and the jaw cylinder, such that an inner surface of the paper guide faces the outer circumferential surfaces of the collect cylinder and the jaw cylinder while an appropriate gap is maintained therebetween and such that the inner surface of the paper guide, together with the outer circumferential surfaces of the collect cylinder and the jaw cylinder, defines a sheet transfer space having a substantially triangular cross section; and the knife and the cutting bar cooperatively cut off a sheet of predetermined length from a web, while the jaw mechanism and the tucking blade cooperatively fold the sheet.
The guide apparatus comprises a guide unit disposed in such a manner as to be able to move between an active position located within the sheet transfer space and apart from the outer circumferential surface of the collect cylinder to such an extent as not to allow the sheet to slack, and a retreat position where the guide unit does not interfere with the sheet transferring from the collect cylinder to the jaw cylinder; a position-changeover drive unit for moving the guide unit between the active position and the retreat position; a printing-speed detection unit for detecting the driving speed of a rotary press and outputting a driving speed signal during printing; and a control unit for outputting, upon reception of the driving speed signal from the printing-speed detection unit, a position changeover signal to the position-changeover drive unit in order to move the guide unit accordingly.
The thus-configured guide apparatus yields the following effects. Even in printing preparation work, which involves frequent start and stop of low-printing-speed operation, a defectively folded sheet does not occur, and thus paper jam, which is potentially caused by a defectively folded sheet, does not occur on the jaw cylinder.
Also, a worker does not need to observe the folder during printing preparation work, and thus laborsaving and enhancement of work efficiency are achieved.